The invention relates to air or other gas phase handling systems and, more particularly, to removal of contaminants from gas phases.
One type of air handling system to which the present invention applies is heating, ventilation and air conditioning (HVAC) systems, which are typically used to supply the heating, ventilation and cooling needs of buildings. Typically, HVAC systems are designed for four primary functions which are (1) exhaust and/or introduce outside air into the building and distribute separately or mix with recirculated air from the building, (2) cool and/or dehumidify the mixed outdoor and/or recirculated air for distribution throughout the building, (3) heat the mixed outdoor and/or recirculated air for distribution throughout the building and (4) distribute air throughout the building.
Typical HVAC systems contain various pieces of equipment and components including heating and cooling coils, air moving devices, air-controlled dampers and particle filters, for example. The size of an HVAC system depends upon several factors including the amount of air to be distributed and conditioned as well as the region and climate in which the building is located.
In order to satisfy building ventilation requirements as set by Code and ASHRAE Standard 62-2001: VENTILATION FOR ACCEPTABLE INDOOR AIR QUALITY, HVAC systems may either supply a prescribed amount of outside air to the building or an alternate amount of outside air can be used if an air purifier is used in the system and an equivalent air quality is provided.
Purifying and recirculating air is desirable as air handled in this manner can be substituted for an equivalent amount of outside ventilation air, which in turn provides reduced capacity, capital cost and energy savings. In addition, humidity is reduced by reducing the source of humidity from the outside air stream during certain times of year, particularly when the outside air is a substantial source of humidity.
However, purification is typically accomplished using gas phase filtration methods including adsorption, in which certain chemicals adhere to the surface, and chemisorption, where chemical reactions occur on the surface of an adsorptive filtration media. Unfortunately, increased energy cost results due to the need to overcome the pressure drop caused by the media, and the media must also be replaced, regenerated and/or disposed of, leading to additional cost as well.
It is clear that the need remains for improved air purification as well as capacity reduction, capital cost and energy savings due to use of such improved air purification capability in HVAC systems and the like.